"The addition of a seventh C-17 to our fleet is a significant milestone that strengthens our support of operations worldwide, especially in Afghanistan," says Peter Luff, minister for defence equipment, support and technology. The type has also been used to support humanitarian relief operations in Chile, Haiti and Pakistan this year by delivering emergency supplies such as tents.

The RAF's 99 Sqn received its first C-17 in May 2001 under a lease agreement covering four aircraft. The UK subsequently decided to buy the transports outright and to also expand its fleet to seven. No more will be acquired, according to the recently published Strategic Defence and Security Review.

ZZ177 will be the last C-17 to enter service with the Royal Air Force

Boeing says it has delivered 224 C-17s, including 20 to international customers Australia, Canada, Qatar, the UK and a consortium of NATO and Partnership for Peace nations. The United Arab Emirates has also ordered six.

The UK is the largest single operator of the C-17 after the US Air Force. However, this status will be assumed by India if the nation finalises a planned deal for 10 aircraft, a preliminary agreement on which was reached during a state visit by President Barack Obama earlier this month.

Now that Etihad Airways has elected to stop funding Air Berlin, forcing the German carrier to file for assembly, a central question is which parts of the business can continue to operate in the long term.